420 



SOILS. 



quently in their migrations. No such need was felt by the 

 inhabitants of the arid regions for centuries, for the native 

 fertility of their soils, coupled with the fertilizing effects of 

 irrigation water bringing plant-food from afar, relieved them 

 of the need of continuous fertilization ; while in the humid 

 regions, the fertility of the land is currently carried into the sea 

 by the drainage waters, through the streams and rivers, causing 

 a chronic depletion which has to be made up for by artificial 

 and costly means. What with the greater intrinsic fertility 

 and the great depth of soil available for plant growth, much 

 smaller units of land will suffice for the maintenance of a 

 family in arid countries ; a fact which is even now being il- 

 lustrated in the irrigated region of the United States, where 

 ten acres of irrigated land instead of 40 or 160, as in the East, 

 form the unit. 



The arid regions were, therefore, specially conducive to 

 the establishment of the highly complex polities and high 

 culture, of which the vestiges are now being unearthed in what 

 we are in the habit of calling "deserts;" the very sands of 

 which usually need only the lifegiving effects of water to 

 transform them into fruitful fields and gardens. It is also 

 quite natural that the wealthy and prosperous communities 

 so formed should in the course of time have excited the 

 cupidity of the " barbarous " forest-inhabiting races, and as 

 history records, have been over and again overwhelmed by 

 them a similar fate often afterwards overtaking the con- 

 querors in their turn, after the Capuan ease of their existence 

 had weakened their warlike prowess. At the present time, 

 the arid regions of the old world are still largely suffering from 

 having been overrun by the nomadic Turanians, whose 

 original habitat Mongolia and Turkestan while also arid, 

 does not permit of the ready realization of the advantages 

 above outlined, on account of the rigorous climate brought 

 about by altitude. Mahometanism first expelled, and has 

 since repelled, occidental civilization from the arid regions of 

 the Old World, remaining to-day as' an obstacle to its prog- 

 ress. The peaceful aggression of railroads and telegraphs 

 now seems likely to gradually overcome this repulsion ; and 

 when Constantinople and Bagdad shall be linked together by 

 the steel bands, the desert will lose its terrors, and Mesopotamia 



